SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26212549ed6c49652a86ebfb73661706d467a1564fed9dc344b23f9c47a88727' 
  AND token = 'secKkRStdv6jnQolseqfTmdUuwZnRvZTCnD0FDTqQcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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