SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0521cfd75a85f33d469ede78745c52f0c14560f97fc89e53c3f74077b9faaf6' 
  AND token = '0zvcgF8w4rC0cDq0CfXsNi1U0JdENsgCad3Kyzn1kvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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