SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87666db951c3ab6e84dfbec1949f5fd3971e642863c68aa92c389547dafeb4ad' 
  AND token = 'qp/atr8Kb8O1Qk2WnIZzN7VsuHapmsKAyZmFtKMCcs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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