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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a02a4581b2c68c2c2b86031a541bd2d8bb75970eb0610192f920ee8d79bd2797' 
  AND token = 'hKbVUT0VJtnV9+heWEQToqHaSuSAY8NfjwrdAlbaxa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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