SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fcdd7d8847e0022b4d69caa4a0e128aada29f851c1a678919b3e810d9785d3' 
  AND token = 'EGRBlizJPwzVCuwNzwOlnPjEpGsr+D4vdXjgM+pWxJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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