SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a29c2b60ba69b0b0039e31da854287f63fef3c989906251008e2a5c1fcf3cff' 
  AND token = 'qKEBfiWwgxO7ws6ci18fH3tJmpymypgPuCsWorVkFuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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