SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fbaa6d73cd59ac11f341b4832937f309eda42fbfa29c40ccaf3c3923f10d6fb' 
  AND token = 'R+MtQt4Gf3ObiJ7c04RM5R3wUawo3+LwnFjDR5pEKDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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