SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55bf8e6ae526615390effe574863ee13f5d82618530bff412bbe33613b7f0b3f' 
  AND token = 'XqGE/BHLoZeJVwKwTf7IutFuq+Gog+q8FOWLHVDInBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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