SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '807b665e82f8d52314e04781421390a5514bf355f2a54846c5ad0e01b101fa23' 
  AND token = 'c/21JBveL3+9eJ9gAvW5jbZfzRSVgQBTFK0p0YxTQoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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