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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '39ecc6138371c81647f5bfb3156aebde311d27a8334dd007588d6d29b83bb6bf' 
  AND token = '84FajgErI3W4PHjeQ4/GMhxb8iSjwvbVMF1e6gVTIQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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