SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55a2bebd66e1e053a856a65ff2e4ba3b6820e83712f5336c472108c189b2b5da' 
  AND token = 'yMhCb3W4lPEryQaVJnVFo5//XkkRWbTJZNyIOM0vlOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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