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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c5636df987e1ff169bae95a0da83ac530b48bcd3d37ef83156095c62fcd93a29' 
  AND token = 'lZ11wkfxI1TJ24F16S62D6vOALYT3UBZPgDT8mqsoI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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