SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '419421f3ea14053f78094134e7584d010985f92964d89c5eab59dd69031f3356' 
  AND token = 'BhjIFLayLL9arjLeo/9QyUmEJodAr/6RYYhqEG27oSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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