SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2a651a51d9e5bebfe20821717d1e1db03f47adadffcc802d4ed09b2f0dc5355' 
  AND token = 'KcZOCyr3kuulkNouX8Qz4Vog5y0gc6HSNmhKUBbwCD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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