SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339b13e7fd33d3ef226ea40f19ec9fdccbbeca120a921c133aec3e8d2b304fb8' 
  AND token = 'qQSPbJwdyjh2468l8ssX7kdDesDencXOuR2eNKtPVbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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