SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759a714c05abba212a683796f48959a380d29e4e472ff86144fb3e9c6b7a14ef' 
  AND token = 'p9tZb2oC1rQhzjoJOAs+uOu/csA29jvBjycGYwouIvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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