SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '171dbb4b487dc90c8f448ad15284057a274be626a0019a7045d255c8ec376daf' 
  AND token = 'UYULuWh560OJvddc0HNbSj6WUiC1FrQt/ZSCb1rN/Oo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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