SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43a8acd0b31e51ee22247d40a63454e6786a1c849073a988ce8382706c53c4f6' 
  AND token = 'eQ2RKi+jSixVoQG9jQvI04FjoUp9+jqDk0MtuCAzHiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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