SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9d6769a1386409ae46c835bc082ec3517a84f9efa661c503ac0297efefcc270' 
  AND token = 'pzmE8g0sSL0+MCoWlKeNnU9bpU8mR2ZPN+RQWoLdI5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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