SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8236b0b9306184d3eb205c79ff4a610d839fb432197c604208afc8e890eb724c' 
  AND token = 'up3+j+OEa3OlCtKENp3W7nclP2aRnqJJ8mNs9zlWejA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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