SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f21802b3df43727bafa03daad0d199982a751c804192e44638c5cdb9ec8689d' 
  AND token = 'E1l5hO1DtL0BBg6Ov5iQEUuAuFfx5/ZA/0se3etl7R8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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