SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8a2c7e12d34783dcf76b875213025712a6cf3dc1fb12be4afc5d02eeb801d14' 
  AND token = 'gWqBZ/JBWeDIPXjirwU95xVRslzl2rJ3WVZG1Ri2LeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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