SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b71bf3aa565a8a2900240be5e574ed2fbd7f54bf85c3284be11df09fc7e2138a' 
  AND token = 'iCZdjaSlW6WDjgs166V0q+sxFAu87ZIvGypIhXF4iGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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