SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '850cd532f846ef90ad2c80cf89d493d631c3227e44210cb2f22b926326c257fa' 
  AND token = 'Smo/pcphKLWIO4/4ISXNK1Tjzg7pO8SToDKtvAX5WT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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