SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab6776b818c40eb09617681633d26174b0c6e97f799889c01c62e971600227bb' 
  AND token = 'XenwvuijeEkc3gfCcyBiBsy6NfEqmAwIUfACsCUxj2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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