SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cf2bd9241cebb9c57d8f46e4fec8e10c624394400f5dd37a22b42677df8f04e' 
  AND token = 'x5oKf5tNl+fIsEuCyJOzJNlyaJRWSp5RTCaaskY67Rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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