SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5d2e0caddf710273392821398b09329ccc382a18c656bfaa0d09d1499e3ab19' 
  AND token = 'A48KMn4lyznaL0mpUxlIQQ/ur8x8BeslMORGE2SvfJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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