SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb7a90602ae969745f71452a54ae825ebb7f40918d7ca7a74956d493d663b683' 
  AND token = 'Mn6751sXAUFPAaue89GJaLalpu+EVmefDzMlGsIjSgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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