SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b684b3f3ce3bbbc9290796a7dc36413b3c4670dead845fec7426fdb5d1d2155' 
  AND token = '8JjGi34wNXta/vJTZA/es4j3PG2NBHLSnGCbgIrklJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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