SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76dbfbb0a6d94a01ec2adc7214f2146cfbcda86d75c48006cb391595c9aa3bcf' 
  AND token = 'OMFTnc3Vzu9TLHKvDTcTvs1YB/z9FqKsSY1Gsy+wJcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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