SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20548783ae1fbe9bd932d835383efa82000455fd6e8408954bbed645c52a47a7' 
  AND token = 'KumpVBHAWn0Hx81+xeSc8f5kxat2Zt3ki6eConIIGuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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