SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4aefc79b2f293888b35c9a969fdd00ff4aabf2be3f9a560c7fab12650d49126' 
  AND token = 'QHuimGqqOYEGRN3y4kcXqZe2UKAqwTtkrqsfowsLJZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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