SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20ebc34344a03de66ced7e8cd66aedae22d2c459843d5d77feb8287640afd964' 
  AND token = 'KeyVJzFtSFKHXSXnn9VCsrg+6RQDvjIWjweqJZ/93C8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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