SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c684d0f5d9266f9fb75d18e68b0677da348c899d65a72cab9ad5d9c4b58d4144' 
  AND token = 'QP8rEmQZ1t1+IySjY+x9eNsaBlbsDOw9WiLuJJnOaRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00094

JSON explain

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