SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66f12dc1da9cfd34c2ab817ec64704e91017e08211ed4362e903e603913aa0bf' 
  AND token = '0p4SUE3CoO6BdKltkXarJYYcOyL5px1l+Gcd+KTWyqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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