SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68bacd00df6d871afd8b66463645a04265314c1a785b85513f1f4491b09d8316' 
  AND token = 'EgenyCY9+caFIOsBLZp0hl81LRZpj7+WJyrZHpIVlLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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