SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86d459aa09313860aaf6fc51576552e7524a389cae520270a2124f4d88e270a9' 
  AND token = 'z+/uPTYr6rTMp0d9jNbefzauAtRPTuXSolWGiDRD1O0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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