SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec014bb7cb56d239f56154a08eef28ff7ce915766077d6f294d05d5cfb058873' 
  AND token = '6/VXmha5yk+bHhhMZ+F7emvHolYsXPMRi0+q/7q5xaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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