SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5dbeb99aa52f9aa538fc9fedc783289b8a440c578601dfbed1b2b4201d2c333' 
  AND token = 'mfQvKLzY3czwrjh6rzjaSApVlMrnXgxqgPJ1rcx+Idk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}