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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cd08ae376d9418a04a0d51ca8e553e3f5c3605d3732128b70528f3f57affa83d' 
  AND token = 'T26n+Six91auq5f/gvXExcDQk10uBNWyBirmz4NYZk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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