SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2ff0a81a7b5e5d0df002cfa1322db6204cb11f628992baac028aedd6321d1e1' 
  AND token = 'O0ZYQDEZNDaSvZVewWUzRHqajb9MwbFFzLRdWckYmRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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