SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1a787697c9f85112676870b3783d544f3350e83215957323a1ac7b8f154f31d' 
  AND token = 'bHmt6sz1eVY8cib9FTWijJ2ZmD6uo2hUV/Ouhl2WNHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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