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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f496995492ad2ca2d9435b06100f0482f2f6cd9750a80dc20ed2bd2a9d379f' 
  AND token = 'I3Mq9VA4Aq8Nt+VKbIl53hPmpgIo2jE4KjGG9WgSlLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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