SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3355f5bf7bea0285683984488d2bdc1382c0e558f064d03d2a21bd29a76326b' 
  AND token = 'uu0lfbhqFR/jB1CZTmJEoJcyFqDZ9rg7X1o3YMMO+F0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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