SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '81589d8a6fd7db0731c874b8872f0105769134245fd838c2eaffd1b3d6066f3f' 
  AND token = 'jRCG9VpTxX1YylOrBT+UBB+vgAdPKfZIIkOxH9dWdSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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