SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3ca3570ab040de84a3a585a715812490fc475082feae5d2522943f807162997' 
  AND token = '2k1wSgvgfAoHRTpIPiypjzJRJTn8OJ3AeTM27M8irZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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