SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff579cc4bbd6b30c44ead9abfadcfe3c29848478cf499484485f4c6143ac8ba5' 
  AND token = 'ElFznhFHRPpB9soE1Hk77hwMiMwc+G71CLcfCsre+2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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