SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b448356288e8f4d239ecd50e54d9bcdbce9c7f745b942f947a5617613823b1fc' 
  AND token = '3elJb/gH665+JVlMbS0wBhQw3WPyjZaHADIykmNm7Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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