SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '29abb1aa2369245df9a38e49d096df431208d8b259466ea566acd7d878daf571' 
  AND token = 'WB/YOdLNQt0/XmK/1fWGZ0Wo2CcM/9hLBS4fMllcMHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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