SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5c832bfdfe17656dce2cb237f835e2bd57d7e2c2e384da592d25b1585dd8934' 
  AND token = '/OhSoynL0GkCWAeGkLXWFkf4nWn4JjofscK73Eji4/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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