SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b026dba928fde2811bb4a46a8354870f490261ceecbda0b4dab2effd2f534cc6' 
  AND token = 'stOLujEepl+rdXjV8QlZ0XC713D3fFvbMZ7NrIELDHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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