SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7950cd16400dbe1c8e3bc925ce4534f3139b31fd798db52408f2f07e1a8e4749' 
  AND token = 'd1nf2wyWy1usTP3GZ0UmBLtqaZ2y+oK0GK+X8uPXyn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}