SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51330f4f0c16d643467db423dfd888dc5f949bb486611fd58f85139aa22ef827' 
  AND token = 'Jivl0ZcX6GID5wiZ2L+kYIji9uzGG1yB0detD3MDHZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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