SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4ef76ce1fe3a8b777f72498f5fc5506796adfa01b14f60861d75e4ab9da21485' 
  AND token = 'jM9kgZ7TwyhSD67q5uuFHUpFqkZsjoLQNZmRmLSQivA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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