SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35263529d07c404c665d857aea4dbf476b44b3816baf735ecbf851bf96b93237' 
  AND token = 'l9mf+yTx3Atg4wxSODwBq6TnEFihE8zDL0nHueycuW8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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