SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16251dc3bd4decb3277c580017648cab800ffee3ade8eab845dac8cfd304393f' 
  AND token = 'NFc/KDhd/98oMY5gxNLRfWBRvzhkJtrVnyQD9jiQbC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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