SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a92cb18277e4b00983dc748f9dd385affdd9dfdf494c1ddb0d700c477437d279' 
  AND token = 'LKwXLwEu3Fz1qdLB+Gs+UinGT5dgd4Y9rtt+vRd0200=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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