SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83f5b1d4367fc5b7f737d19847e90178ebfc7b1d6f82145274efb3c8ea786437' 
  AND token = 'qQyQxblPItb8ReU+zi2mMeTMbCNbaGavLnm0eyocNL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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