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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'efd6e0734035d4d903c7451b34effda0fbfef404b388cfbfafbd2a4c35e52f82' 
  AND token = 'zvkyW+kn861VUPhYG9BTs44CAn9otKvuNSvxVQOv/bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}