SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5751fd8117665d83d0a2ee8a2eebe86bf0864ba3903faa507cb0921f699ffc02' 
  AND token = 'LQGOwO9x7LMlWwbbxOh+crfEBHTo4ZbRdqZO+9lP3pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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