SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff659a5d8464c9abfb2282dbc023e6e7557b889f1ba42ff14d01781c76401f1' 
  AND token = 'kyOtLULwZP/RUnwb9JkqYh8jG+twuyGxoga/wQDprUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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