SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eb9e44007a119e23bc21a862af90f3cfd1f49ca7a3519405f349b775f36573a' 
  AND token = '7mAj/G65+ZjngLxbhUbo2sn4Svq4cdPmMRCVJVtTUSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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