SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc465a1ec186a69926045d92545036cf21cf0e6d13f7b1634f906ef74936d691' 
  AND token = 'xC65ET0lTIhJimS3S37etZIeYYmefoHjcQz1kBSsUMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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