SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f9223e434f3d55f045501556dd1570c7a25000cf606369f8c912695163bc081' 
  AND token = '3+NaEAaWrhyLIw4RDH779kUnbQxHkGPICq/t9EPRuwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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