SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847afc321e5a27aa3320813ccc555d45a9ad555960ffe22cdb73aaae1d2cbb5a' 
  AND token = 'PFAWm/qthHgGy+0jrKDacqqIfOBR8VgEa+gIqORPEZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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