SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ee2016ba39abcc16a2a7f75585a02f2ffa07f6aa6dbb8c45115fd0498fba06ba' 
  AND token = 'DZwIdMwwimWBu2g/dQmNPQPp3PHnp97i98tuQotsAro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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